The subject of this invention is a programmable cylinder lock, namely a lock comprising devices intended to allow providing the initial codification of the lock or, through a change operation, to modify the former lock codification in order to adjust the lock for being operated by a key different from the key to which the lock was formerly adapted.
More particularly, the invention concerns improvements in a kind of programmable cylinder lock which is known from the European Patents Nos. 0.226.252 and 0.900.310.
In a usual cylinder lock, which comprises a stator and a cylindrical rotor mounted inside the stator for rotation around its own axis and having a keyhole extending in the axis direction for the insertion of a key, a number of locking pins are mounted inside the rotor, movable perpendicularly to the axis on the extension of the keyhole plane, and each locking pin is intended to cooperate with a key segment whose codification is represented by the level of a tooth or recess of the key, situated within the considered segment. The fixed length of each locking pin is such that, when it cooperates with the corresponding segment of the correct key, the distal end of the locking pin corresponds to the cylindrical surface of the rotor and does not hinder its rotation, whereby, when all the locking pins are displaced in the respective correct positions by the correct key, the rotor can be rotated for operating the lock. When, on the contrary, one or more locking pins are situated in non correct positions, they (or the corresponding counterpins which may be provided in the stator) extend through the cylindrical rotor surface and hinder its rotation and therefore the lock operation. Because the codification of the lock is represented by the fixed length of the locking pins, that is defined during the manufacture step, the lock can be operated only by a single correct key and cannot be otherwise programmed.
The programmable cylinder locks of the kind considered in this invention and described in the mentioned patents comprise, in the rotor which is rotatably mounted inside the stator, instead of locking pins of a preestablished length, a number of key followers movable along their own longitudinal and transversal directions, said key followers being intended to cooperate with the codification conformations of a key inserted into the rotor keyhole, and a corresponding number of locking pins movable along their own longitudinal direction, which form the blocking members of the lock. The key followers and the locking pins form together a number of pairs each including a key follower and a locking pin, and they are provided with toothings intended to mutually cooperate, in different relative positions, in order to define the lock codification. A transversally displaceable stop bar cooperating with a longitudinal groove of the stator and having projections susceptible of cooperating with notches of the locking pins has the purpose of immobilizing the locking pins when the rotor is made to rotate within the stator and, as a consequence, the stop bar comes out of said groove and engages the locking pins. A change bar, which is transversally displaceable and is slidingly coupled with the key followers, normally keeps the key followers engaged with the locking pins but, when said change bar comes into said groove of the stator, it transversally displaces the key followers and disengages the same from the locking pins, thus allowing to modify the lock codification by means of the replacement of the former key by a different key.
In a lock of this kind it is required that the number of possible codification combinations, namely the number of different keys foreseen for the different locks of the same kind, be the higher possible. One of the parameters which determine the number of possible combinations is the number of codification levels that may be foreseen for the key segments, and this number depends on the pitch of the cooperating toothings of each pair of key followers and locking pins. The more small is this pitch, the more high is the number of possible codifications. However, the pitch of these toothings cannot be reduced below certain limits, on one hand because this would involve greater manufacture difficulties, and on the other hand because the engagement between the pairs of key followers and locking pins would no more have a sufficient mechanical strength.